This invention relates to a knife with folding blades, and, more particularly, to such a knife having a simplified locking mechanism.
Knives are commonly available with either fixed blades or extendable blades. The fixed blade knife, whose blade is permanently fixed in the extended position, is popular with outdoorsmen because it is strong and can be provided with features particularly useful in hunting, fishing, and other outdoor activities. The extendable blade knife, on the other hand, can be provided with multiple blades and many more features than the fixed blade knife. The extendable blade knife is also more compact than the fixed blade knife for carrying and storage. The most popular type of extendable blade knife is the folding blade knife, and the present invention relates to such folding blade knives.
The folding blade knife has a knife body and at least one pivot pin. The blade or blades are pivotably mounted to the pivot pin or pivot pins. The knife has a retention mechanism to hold the blades in the closed position, within the knife body, until the user of the knife selects one of the blades for use. The selected blade is controllably extended by rotating it about its pivot pin to the open position.
A locking mechanism may be provided to lock the selected blade in the open position in a manner that permits later selective unlocking of the blade and pivoting it back to the closed position. Alternatively, there may be provided no locking mechanism for the extended blade, so that the user holds the blade in position during use.
A number of locking mechanisms are available for use with opened blades of folding knives. In one approach, the mechanism includes a spring bearing on the blade to create an overcenter arrangement which retains the blade in the closed position until forced open against the spring force by the user and also holds the blade in the open position until forced closed. The spring mechanism creates a force that tends to return the blade to the closed position once the overcenter position is reached. There may be a positive lock of the blade in the extended position, such as in the well known lockback configuration. In another approach, a detent structure holds the blade in the closed position, and a lock is provided to lock the blade in the open position. In this case, there is no spring force tending to close the blade.
In yet another approach, a side lock plate is placed laterally adjacent to the blade to be locked. The side lock plate includes a finger that is biassed toward the blade to be locked. The blade is normally held closed by a detent mechanism. When the blade is opened, the finger locks the blade in the open position. The user later selectively unlocks the blade so that it can be folded closed by depressing the finger and disengaging it from the blade.
Various other locks and combinations of closed-position retention mechanisms and open-position locks are known. More complex locking mechanisms have been devised, but these complex mechanisms are costly to produce and more prone to failure than a relatively simple locking mechanism.
These various retention and locking mechanisms are all operable and useful in various situations. However, each has its disadvantages. The proper operation of the spring closure requires the use of both hands to open and close the knife, a distinct disadvantage for some users. (Some users attempt to open such a spring closure by employing another part of the body, such as the thigh, to support the blade during opening or closing in order to use only one hand--this has resulting in cutting of the user in some cases.) A separate positive lock typically adds weight, cost, and complexity to the knife. Also, a separate locking mechanism is typically required for each blade, so that the knife becomes complex, heavy, and unwieldy when there is a provision for locking more than one blade in its open position. The result in that in most instances a knife will have only a single blade where there is to be a positive lock for the open blade.
There is a need for an improved retention and locking mechanism for folding knives. The locking mechanism should be operable with two blades that are to be locked in the open position and releasably closed. The locking mechanism should permit one-handed operation by the user of the knife. Desirably, the locking mechanism would be inexpensive and simple in construction. The present invention fulfills this need, and further provides related advantages.